Method and apparatus for the elimination of defective sheets or packs of sheets emanating from machines for producing sheets



1967 E. KLUTH 3,335,625

METHQD AND APPARATUS FOR THE ELIMINATION OF DEFECTIVE SHEETS OR PACKS OF SHEETS EMANATING FROM MACHINES FOR PRODUCING SHEETS Filed July 12, 1965 United States Patent "ice.

3,335,625 METHOD AND APPARATUS FOR THE ELIMINA- TION OF DEFECTIVE SHEETS OR PACKS OF SHEETS EMANATING FROM MACHINES FOR PRODUCING SHEETS Engelbert Kluth, Dusseldorf, Germany, assignor to Jagenberg-Werke A.G., Dusseldorf, Germany Filed July 12, 1965, Ser. No. 471,228 Claims priority, application Germany, July 17, 1964,

26,224 5 Claims. (Cl. 83-27) ABSTRACT OF THE DISCLOSURE The invention relates to eliminating defective sheets and packs of sheets in which the defect is determined on a moving web and stored as an impulse until the sheet containing the defect reaches an eliminating means and is directed to the concept of passing the defect impulse through an electronic distance measuring means at the speed of the moving web. The defect impulse leaving the electronic distance measuring means is stored and such impulse is discharged only after the receipt of a cutting impulse as an activating impulse for actuating the eliminating means with the distance covered by the impulse being ascertained by the size of the sheet format to be cut.

The present invention relates to a method of and apparatus for the elimination of defective sheets or packs of sheets emanating from machine for producing sheets wherein the defect of flaw is discovered in the moving web and is stored as an impulse until the sheet having the defect or flaw reaches an eliminating or discarding zone.

A method and apparatus for the elimination of packs of sheets including paper sheets or the like containing adhesion spots or marked defects is known. The packs of sheets or superimposed webs to be cut subsequently into packs of sheets are conveyed through an apparatus in which on the passage of adhesion spots or other defects there is triggered or initiated an impulse which effects the elimination of the packs of sheets containing the defects. In such apparatus, a condenser is utilized and which condenser changes in capacity when sheets having an adhesion spot or defect passes therethrough and the change in capacity which is measured in the high frequency field initiates an electrical impulse at the output of an amplifier. Since the condenser is located at a distance from the transverse cutting mechanism which corresponds to the maximum sheet format length to be cut, the impulse cannot be used immediately for triggering the activation of the eliminating means. The positioning of the condenser at a shorter distance results in sheets with defects at their rear ends entering the stack of sheets since the front end of such a defective sheet has already passed the eliminating means when such eliminating means had been actuated by the impulse. The above necessitates a storing of the impulse and which must be maintained until the sheet having the defect has reached the zone of the eliminating means. The storing of the impulse in this apparatus is achieved by the aid of electronic counting tens which control the eliminating means. However, it has been ascertained that the setting of such counting tens is quite complex and time consuming and additionally requires rather extensive calculations and the use of tables. Furthermore, such arrangement does not provide for an accurate elimination of the defective sheets, particularly in the case of several defective sheets moving in direct sequence.

3,335,625 Patented Aug. 15, 1967 The salient object of this invention is to provide a method and apparatus for the storing and passing along of the defect or flaw impulse with the duration of the storage being dependent on the size of the sheet format to be cut.

The solving of the problem according to the invention comprehends the concept of running the defect impulse through an electronic distance measuring device at the speed of the moving web for subsequently triggering the actuation of the eliminating means, the distance of the path to be covered by the defect impulse being determined by the distance measuring device in accordance with the size of the sheet format to be cut, the impulse passing through the distance measuring device in step by step fashion with the step sequence being ascertained by means which measures the moving web section by section and the impulse emanating from the distance measuring device being then stored and released from storage as an activating impulse for the eliminating means only after the receipt of a cutting impulse.

The apparatus includes a defect scanning means connected in series with a cross cutting means, the scanning means also being connected with an electronic distance measuring means defined by a shifting storage device, the distance measuring means being connected by way of an interrogation storage means with means for activating an eliminating means.

To control the stepwise passage of the defect impulse fed to the distance measuring means by the defect scanning means, there is provided an impulse transmitter operably coupled to the web feed and the distance measuring means is connected with the interrogation storage device via a format adjusting means. Also associated with the cross cutting means is an impulse transmitter influenced by the cut and which feeds impulses to the interrogation storage device with such impulses and the output impulses of the distance measuring means serving to trigger the activation of the eliminating means.

Furthermore, there is provided between the output of the interrogation storage device and the means for activating the eliminating means, a counting means which, in accordance to its adjustment, determines the time of opening of the eliminating means in such a manner that one or more consecutive sheets or packs of sheets can be eliminated or discarded. The elimination means is located behind the cross cutting means at a distance which is less than the smallest sheet format to be cut and such arrangement is necessary since the activation of the eliminating means occurs at the instant of the cut and the immediately cut defect free sheet format must not yet be discarded.

Additional objects and advantages of the invention will become more readily apparent to persons skilled in the art from the following detailed description and drawing and in which drawing the single figure illustrates diagrammatically in side elevation a cross cutting machine incorporating the invention.

As illustrated in the drawing, a paper or kindred web 20 is withdrawn from a supply roll 21 by a pair of rollers 22 located above and below the web and is conveyed into the area of a transverse or cross cutter assembly 23. Following the cross cutter assembly 23 is an eliminating device 24 and by means of which proper sheets are moved to a stack holder 25 and defective sheets to a holder 26.

In order to detect defects in the moving web 20, there is positioned directly in advance of the rollers 22 a condenser unit 27. The condenser 27 is connected with an amplifier 29 by a conductor 28 with the amplifier in turn being connected via lead 30 with an electronic distance measuring means 31. The distance measuring means 31 is constituted by a shifting storage device.

A conductor 32 couples the amplifier 29 with an impulse transmitter 33 which in turn is operably connected to the rollers 22. The distance measuring means 31 includes a plurality of electronic switching components whose switch conditions are indicated by indicator lamps -18. The measuring means 31 is further connected by a multiple cable 34 with a format adjusting assembly 35 and the assembly 35 via movable switch arm 36 and lead 37 is coupled with an interrogation storage device 38.

The storage device 38 is connected by conductor 39 with an impulse transmitter 40 which scans or probes the cross cutter assembly 23 and the output of the device 38 is coupled via line 41 with an electronic counting unit 42. The unit 42 includes a preselection switch 43 which, by conductor 44, is operably connected to a magnet 45. The armature of the magnet 45 via the pivotally interconnected levers 46 and 47 triggers the activation of the eliminating device 24.

The eliminating device 24 is in the nature of a switch located at the entrance of upper and lower endless conveyors 48 and which conveyors cooperate to move the cut sheets to the holder 25. The device 24 pivots about the axis of the forward roller of the lower conveyor belt and is of a length to correspond substantially to the width of the web 20 and the length of the cutter unit 23.

The operation of the apparatus is as follows:

The web 20 Withdrawn from the supply roll 21 is moved in a stable condition through the high frequency field of the condenser 27 and the capacity of the condenser is determined essentially by the geometric measurements and by the layer of the web disposed therein. If the thickness of the paper layer changes, the capacity of the condenser also changes and the more sharply the thickness of the layer changes, the greater the change of the condenser. This alteration in capacity which is measured in a high frequency field generates an electrical impulse and the strength of the impulse is dependent on the magnitude of the change. In the case of adhesion spots or tears in the paper, the thickening or thinning, respectively, of the web becomes effective in the condenser thus providing a positive electrical impulse in each situation.

Since the above mentioned defect impulse is tobe utilized for actuating the eliminating device 24 and since the condenser 27 is located in advance or forward of the cutter unit 23 at a distance A which corresponds to the greatest format length to be cut, the defect impulse must be stored and shifted in correspondence with the speed of movement of the web 20. This operation is accomplished by the distance measuring means 31 which receives the impulse by way of the amplifier 29' and shifts the impulse along with the speed of the paper web 20. In the initial position, all electronic switch components together with indicator lights 0-18 are in the off condition and if a defect is detected by the condenser 27 an indicator light having the number 0 is illuminated in the distance measuring means 31. Simultaneously, the impulse activates the transmitter 33 which is coupled with the feed rollers 22 for the web and in dependence on the web feed movement delivers in regular sequence an impulse into the distance measuring means 31 via the amplifier 29. The first shifting impulse causes the indicator light 0 to be extinguished and the light 1 to be illuminated. The second shifting impulse extinguishes light 1 and illuminates indicator light 2 and, in the embodiment shown, the indicator light 18 is reached after eighteen shift impulses at which time the defect impulse has travelled entirely through the distance measuring means 31. Hence, the adhesion spot or defect has moved throughout the distance A and is now in the zone of the cutter unit 23.

To realize an orderly elimination of the sheets having the defect, the eliminating means 24 must then be activated if the sheet format which at the instant of the cutting step is located before the cutter unit 23 contains a defect For this reason, the impulse passing through the distance measuring means 31 in dependence on the size of the sheet format is picked up by various switch components. By the position of the switch arm 36 it can be ascertained at which particular switch component the continuous impulse is being picked up and the arm 36 can, by way of contacts 0"-18', be connected with each of the switch components of the measuring means 31 so that, depending on the length of the sheet format to be cut, the impulse is delivered earlier or later to the interrogation storage device 38. The storage device 38 further receives with each cut an impulse from the scanning means 40 and thus the storage device 38 passes on an impulse to the counter unit 42 only if at the instant of the out there is on hand an impulse from the measuring means 31 via the format adjusting device 35.

The output impulse of the storage device 38 activates the counter unit 42 as follows:

With the preselection switch 43 in position I, the impulse-from the storage device is used directly for activating the magnet 45 for actuating the eliminating means 24. At this position of the switch 43, the eliminating means 24 remains open only for the elimination of one sheet format. To eliminate two or three sheet formats which is necessary if the sheets are conveyed and deposited in an overlapping relationship, the switch 43 is set at positions II and III, respectively.

For example, if the length of the sheet format to be cut is 600 mm., the path 600 mm. in advance of the cutter unit 23 must be surveyed or studied for incoming defects. Accordingly, the inspection must start at the indicator light 12 and the switch component associated therewith if the transmitter 33 yields one impulse for each web advance of mm. For this purpose, the switch arm 36 is positioned at contact 6' and each defect impulse in the distance measuring means 31 which passes light 12 is delivered to the storage device 38 by way of the switch arm 36 and as previously mentioned is passed on to the magnet 45.

The present invention constitutes a defect delay arrangement and by virtue thereof it is possible to eliminate every defective sheet including directly successive sheets in the event for reasons of an overlapping conveying and deposition several sheets are to be eliminated. In the case of the shearing of adhesive spots, the invention provides for a double elimination so that the sheet with one portion of the adhesive spot at the end thereof and the other portion at the advance end of the suceeding sheet will be discarded. To be able to eliminate such sheets, use is made of the fact that an adhesive spot provides a thickening of the paper and initiates an electrical impulse upon entering the measuring area While upon the spot leaving such area, a thinning of the paper occurs which also generates an electrical impulse. Consequently, a positive electrical impulse is generated at the beginning as well as at the ending of an adhesive spot. If a cutting impulse from the scanning means 40 develops between these two impulses, the counter unit 42 is influenced by an electronic storage stage (not shown) in such a fashion that the eliminating means discards both sheets containing the flaw.

What is claimed is:

1. A method for the elimination of defective sheets and packs of sheets wherein the defect is determined on a moving web and stored as an impulse until the sheet having the defect has reached the zone of an eliminating means, comprising passing the defect impulse through an electronic distance measuring zone at the speed of the moving we'b, storing the defect leaving the electronic distance measuring zone, and discharging such impulse only after the receipt of a cutting impulse as an activating impulse for actuating the eliminating means with the distance covered by the impulse being ascertained by the size of the sheet format to be cut.

2. The method as claimed in claim 1 including passing the defect impulse stepwise through the distance measuring zone and determining the stepwise sequence by measuring the path to be traversed step by step.

3. An apparatus for the elimination of defective sheets and packs of sheets wherein the defect is determined on a moving web and stored as an impulse until the sheet having the defect has reached the zone of an eliminating means, comprising a transverse cutting means for the moving web, a defect scanning means connected in series with the transverse cutting means, an electronic distance measuring means defined by a shiftable storage device connected to the defect scanning means, an interrogation storage means coupled to the distance measuring means, a format adjusting means connecting the distance measuring means to the interrogation storage means, and an impulse transmitter operably associated with the transverse cutting means and influenced by the cutting of the web for feeding impulses to the interrogation storage means together with the output impulse of the format adjusting means for activating the eliminating means.

4. The apparatus as claimed in claim 3 including feed means for the web and an impulse transmitter coupled with the web feed means for controlling the stepwise passage of the defect impulse fed by the defect scanning means into the electronic distance measuring means.

5. The apparatus as claimed in claim 3 including an adjustable counter means connected to the output of the interrogation storage means for determining the opening period of the eliminating means so that one or more successive sheets can be eliminated.

References Cited UNITED STATES PATENTS 2,433,685 12/1947 Dowel] 83-80 2,950,640 8/1960 Camp 8380 X 3,169,428 2/1965 Owen 83-27 ANDREW R. JUHASZ, Primary Examiner. 

1. A METHOD FOR THE ELIMINATION OF DEFECTIVE SHEETS AND PACKS OF SHEETS WHEREIN THE DEFECT IS DETERMINED ON A MOVING WEB AND STORED AS AN IMPULSE UNTIL THE SHEET HAVING THE DEFECT HAS REACHED THE ZONE OF AN ELIMINATING MEANS, COMPRISING PASSING THE DEFECT IMPULSE THROUGH AN ELECTRONIC DISTANCE MEASURING ZONE AT THE SPEED OF THE MOVING WEB, STORING THE DEFECT LEAVING THE ELECTRONIC DISTANCE MEASURING ZONE, AND DISCHARGING SUCH IMPULSE ONLY AFTER THE RECEIPT OF A CUTTING IMPULSE AS AN ACTIVATING IMPULSE FOR ACTUATING THE ELIMINATING MEANS WITH THE DISTANCE COVERED BY THE IMPULSE BEING ASCERTAINED BY THE SIZE OF THE SHEET FORMAT TO BE CUT. 